Heliogen targets 1500°C solar thermal

https://www.vox.com/science-and-health/2019/11/19/20970252/climate-change-solar-heat-heliogen-csp

by nclzz • 7 years ago

102 74 7 years ago

new2992• 7 years ago

Bill Gross, Heliogen’s current CEO previously founded eSolar. eSolar proposed using an array of Heliostaticly controlled mirrors to direct light toward a solar cell: https://en.wikipedia.org/wiki/ESolar So... that part of the eSolar approach is carrying over into Heliogen.

Last time this was posted the “AI” component of the play was less clear... But with an array of mirrors, in particular being to generate heat in some volume I guess a more complex feedback/control system may be required.

s_Hogg• 7 years ago

Are we talking about PIMCO Bill Gross here? If so, how did he wind up doing this?

arethuza• 7 years ago

Different Bill Gross:

https://en.wikipedia.org/wiki/Bill_T._Gross

ReptileMan3• 7 years ago

What exactly do you need AI for except for buzzwording? It is not as if the sun/earth trajectory or rotation speed is random. You can precalc with ease at every point which is the best position for each mirror.

viraptor• 7 years ago

That did strike me as weird. Although they say "advanced computer vision software" so maybe they do some workaround and take the position from a camera rather than pre-calculations? Can it be the case that a few thousandths of a degree matters here and that's beyond our generalised model?

truculent• 7 years ago

Perhaps weather/clouds/objects are a thing that must be adapted to?

new2992• 7 years ago

I would imagine that it’s not the suns location that is the primary concern, but where you are directing the light.

The light is being reflected and focused by mirrors. That light is being directly onto some volume of material. So, in this case, they want to get the material above some critical temperature (e.g. so it melts). I imagine that uniformly heating the whole volume may not be the best approach, or that you may be able to work with smaller volumes depending on your expected solar input etc.

So I can see a little more justification here than the case where solar cells are just being pointed at the sun.

pjc502• 7 years ago

The difficult problem is not knowing where the sun is but knowing where the ground is. Since all the panels are separate structures not on a single rigid slab, ground "settling" can tilt them fractionally in unpredictable ways.

It sounds like what they have is machine vision as a novel input into a conventional control loop. For one panel at a time, wiggle it about and look how the light spot changes. Find the local maximum for tightest spot. That's now "locked" in the PLL sense and should stay locked for days or weeks.

ovi2563• 7 years ago

Yes, you can precalc, and then you need very precise actuators to move the mirror to that precalced position.

You also need precise surveying of the ground site to know its geometry. The precise actuators and surverying are expensive.

Their approach is using cheap actuators in a closed-loop system where a computer vision controller (using the four cameras on top of the tower) moves the mirrors until it gets it right. Cheap actuator slip and lag is terrible, but with the feedback of the closed-loop, it's doable.

This is an approach that's now allowing hobbyists to build cheaper motorised telescopes, robot arms and so on.

Juliate2• 7 years ago

https://en.wikipedia.org/wiki/Odeillo_solar_furnace

"started operating in 1970", "Temperatures above 3,500 °C (6,330 °F) can be obtained in a few seconds".

Not dismissing this press release, but at least some scale of progress should be used to compare against. Or state where the economical/industrial/regulatory innovation stands.

scoopertrooper• 7 years ago

That thing is the size of a building though.

Juliate2• 7 years ago

Granted. Size and lightweightness are definitely a point - that could be emphasized as a major argument - even the ratio with size & power capacity & heat intensity.

baq• 7 years ago

yeah the only problem is the useful heat is contained in a very small area/volume, so this is only a research facility.

reportgunner• 7 years ago

AFAIK the solar towers actually use molten salts to store the heat in tanks so they can keep going even overnight.

masklinn3• 7 years ago

It's a solar furnace / oven not a solar power tower.

Odeillo's purpose is to heat things very high and very quickly, not to produce power. It's a tool for materials research not a solar power demonstrator.

There is a solar power research site nearby: https://en.wikipedia.org/wiki/Themis_(solar_power_plant)

thinkcontext2• 7 years ago

Here's a better article which explains the advantages over traditional CSP.

https://www.vox.com/platform/amp/science-and-health/2019/11/...

TL;DR Traditional CSP is aligned once, Heliogen aligns continuously. This allows them to correct for individual panel changes in warping, settling, weather, dust, etc. This approach also allows them to use cheaper hardware.

baybal22• 7 years ago

Well... no.

Motors and circuitry on each mirror instead of a simple screw drive are certainly not making the setup cheaper

It smells to me like a second Solindra in making

dang• 7 years ago

Ok, we've changed to that URL from https://www.theengineer.co.uk/bill-gates-heliogen-solar-ther.... Thanks!

We'll keep the original article's title, since it's more specific.

zubspace• 7 years ago

Another similar project in the mojave desert incinerates 6000 birds a year [1]. I wonder, how they handle that..

[1] https://www.sciencealert.com/this-solar-plant-accidentally-i...

BurnGpuBurn• 7 years ago

I was just wondering how many birds this would fry, thanks for the article.

VBprogrammer2• 7 years ago

The problem is generally trivial compared to the number killed by domestic cats and glass windows.

kwhitefoot• 7 years ago

Is 6000 birds a year a lot? It's a serious question, I have no idea what fraction of birds in the area that is.

Is it comparable to the normal fluctuation in bird mortality in the area or is it so large that it has a disturbing effect on the population?

Of course fewer bird deaths would be good, and zero would be better.

But these bird deaths are noticed because of where they occur. What is the 'background' level, the death rate in the same place without the solar plant?

The Ivanpah installation is on a known migration route, presumably most other such installations will cause fewer bird deaths simply by not being on such a heavily used route. The article was a bit light on background information and I don't know how to find it.

giarc2• 7 years ago

I recall seeing a chart one day that showed bird deaths by source. Death by domestic cats were magnitudes higher than any other source.

honopu• 7 years ago

I think the point of calculating using imaging vs a model that requires layout and flat land etc is this would be cheaper to build. You have to build one collection tower/ target, and the mirrors can aim themselves. This greatly reduces the grading, measurement etc and makes installing on existing land without needing to flatten at all, or to some crazy tolerance, much easier. I can see this used in rolling hills, with less impact etc possible.

tempodox• 7 years ago

Inertia must be incredibly strong. Otherwise, why did it take so long to come up with something that strikingly simple? The last time someone allegedly had an idea like that was around 212 B.C., in the defense of Syracuse.

trickstra• 7 years ago

Because of oil lobby mostly. The idea is nothing new, it was just easier to burn oil instead of building new industry from ground up and going against all existing oil companies.

nradov• 7 years ago

That "oil lobby" conspiracy theory is such nonsense. There are several developed countries with minimal oil reserves and no domestic oil companies. If alternative energy industries were really practical before then those countries would have built it.

gnode• 7 years ago

The technology is fundamentally simple, but not practical on a small scale. There are plenty of large, yet simple projects which nobody cares to invest in because there are better (including more expedient, or proven) alternatives.

CSP requires a large investment compared to PV solar, as it needs to be done at scale to make coolant systems, towers, turbines and generators cost effective. It needs its own large allocation of land, rather than be distributed. It also, like PV solar, has poor temporal availability, so compares badly to fossil fuels, nuclear and hydro.

It has potential to be cheaper than PV, and integrate well with thermal energy storage. It could also be more efficient, if the temperature can be increased (due to Carnot efficiency). However, the convenience and falling prices of PV panels may prevent CSP becoming popular.

masklinn3• 7 years ago

Inertia must be incredibly strong. Otherwise, why did it take so long to come up with something that strikingly simple?

It didn't? There are both solar ovens and solar power plants in active use.

The issue's mostly that it's historically been fairly inefficient and expensive (compared to other electricity production sources). Prices have been coming down through improved efficiency and economies of scale, the plants being built these days are bid under $75/MWh and construction has been ramping up a lot especially in high-irradiation locations e.g. Morocco onlined their first station in 2017 (510MW CSP, 72MW PV) and is already building a second one, and Dubai is apparently aiming for 5GW installed by 2030.

Tangokat• 7 years ago

I wonder who Heliogen hired to do their PR. Must be a really good (or expensive) campaign. There is nothing new in high temperatures and the AI part is pure buzzwords.

epistasis• 7 years ago

I imagine that being able to throw around the name Bill Gates is as big an advantage as a good PR firm.

aj7• 7 years ago

Very skeptical that this is a practical means to supply 1500C to an industrial process. Do they plan on piping heat via liquid metal, or what? Do you shutdown on cloudy days and sen everyone home?

arcticbull• 7 years ago

Just store some molten salt in a really big thermos

astrodust2• 7 years ago

Since thermal energy is only lost at boundaries, the larger the amount you have, the smaller the net surface area per unit of volume.

This is how you can store huge blocks of ice well into the summer (e.g. https://en.wikipedia.org/wiki/Ice_house_(building)), but also how a giant underground mass of molten salt that's not in physical contact with the surrounding ground could store a lot of heat for a long time.

nanomonkey• 7 years ago

I'd love to see something like this put into use for smelting titanium. We really need to start embracing it as a building material as it doesn't corrode or break down like wood, steel, aluminum does...plus it's light and strong which would allow moving houses and vehicles made from it much less energy intensive. It would be great to invest the energy into building materials that can last instead of continuously having to fight corrosion.

Heliogen targets 1500°C solar thermal

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